JPH07231334A - Communication system and connection processing method - Google Patents

Abstract

PURPOSE:To improve the reliability of connection establishment processing by increasing the opportunity of retry of connection processing after the failure of connection concerning the communication system for performing communication by transmitting a connection establishing request through a repeater system to an opposite side system and establishing connection with the opposite side system. CONSTITUTION:A detailed code is added to a connection failure report at a repeater system 3 to discriminate whether the factor of failure is existent at the repeater system 3 or an opposite side system 2 when the connection is failed corresponding to the connection request of a present side system 1, that detailed code is discriminated at the preset side system 1, and the connection request is issued again through another route as needed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention sends a connection establishment request to a partner system via a relay system,
The present invention relates to a communication system that establishes a connection with a partner system and performs communication, and a connection establishment processing method.

[0002]

2. Description of the Related Art Conventionally, for example, OSI (Open Systems Int.
erconnection) protocol is used to establish a connection between the local system and the remote system,
A connection establishment request is sent to the defined route (or the first candidate route when multiple routes are defined). At this time, as shown in FIG. 7, communication may be performed from the local system 91 to the partner system 92 via the relay system 93. The network configuration shown in FIG. 7 is CLNP (Connectionless Network Protocol) in the N (Network) layer protocol in the OSI protocol.
1) and CONP (Connection Network Protocol) are used as an example.

In FIG. 7, reference numeral 91 is an own system, 92 is a partner system, 93 is a relay system A, 94 is a relay system B, 95a to 95e are LAN devices, and 96a and 96b are W.
Represents an AN device.

The local system 91 has two pieces of route information as route information for the partner system 92.
5a is defined as the first candidate route, and the LAN device 95b is defined as the second candidate route. Here, in order to establish a connection from the own system 91 to the other system 92, the own system 91 sends out a connection establishment request as described above. The connection establishment request in this example is CR_TPDU (Connection Request Transport).
Protocol Data Unit). This is sent to the LAN device 95a which is the first candidate route.

Upon receiving the connection establishment request from the local system 91, the relay system A 93 operates as a partner system 92.
Performs route selection processing for the destination. FIG. 8 shows the relay system A93.
2 shows a flow chart of the route selection process.

In FIG. 8, the relay system A93 receives the data from the local system 91 and starts the following processing (step 110). First, the attributes of the reception route (route from the local system 91 to the relay system A93) are determined (step 111). Attribute is LAN (CLNP
If it is “use”, use route of the same attribute (relay system A
It is judged whether or not there is a candidate for the route from 93 to the partner system 92) (step 112), and if there is a candidate, the reception data is sent to the LAN device 95e on the used route (step 113). If there is no use route candidate having the same attribute, connection establishment processing is started (step 114) and it is determined whether there is a use route candidate (step 11).
5). Here, if there is no candidate, the LAN device 9 on the reception route
Connection failure notification DR_TPDU (Disco
nnect Request Protocol Data Unit) (step 116). If there is a candidate, a connection establishment request is sent to the use route (step 117). It is determined whether or not this connection establishment has succeeded (a response has been received) (step 118), and if successful, a connection establishment success notification is returned to the reception route (step 119). If unsuccessful, connection establishment failure notification DR_T on the reception route
The PDU is transmitted (step 120).

In the attribute check of the acceptance route in step 111, if the attribute of the acceptance route is WAN (using CONP), it is determined whether or not there is a candidate for the use route having the same attribute (step 121). If there is a candidate, the acceptance data is sent to the use route (step 122). If there is no use route candidate with the same attribute, connection establishment processing is started (step 123), it is determined whether there is a use route candidate (step 124), and if there is no candidate, a connection establishment failure notification is given to the reception route. The DR_TPDU is transmitted (step 125).

If there is a candidate, a connection establishment request is sent to the use route (step 126). It is determined whether the connection has been established successfully (a response has been received) (step 127), and if successful, a connection establishment success notification is returned to the reception route (step 128). If failed, connection establishment failure notification DR_TPDU in the reception route
Is transmitted (step 129).

In the requesting own side system 91, DR_TPDU (Disconnect Reques) which is a connection establishment failure notification from the partner system 92 or the relay system A 93.
Retry processing is performed when t Protocol Data Unit) is received.

FIG. 9 shows a retry processing flow in the local system 91. In FIG. 9, the following processing is started upon receipt of the connection establishment failure notification (step 13).
1). The reason for disconnecting the connection establishment failure notification is determined (step 132), and if retry is unnecessary, the connection establishment failure process is called (step 142).

If a retry is necessary, the tried route is confirmed (step 133), and it is determined whether there is a candidate for a route having the same attribute (step 134). If there is a candidate, the connection establishment process is started (step 135), a connection establishment request is created (step 136), and the connection establishment request is sent (step 137). If there is no candidate, the attribute of the route used is changed and the connection establishment process is started (step 1).
38). It is determined whether there is a candidate for the changed use route (step 139). If there is a candidate, a connection establishment request is created (step 140) and the connection establishment request is sent (step 141). If there is no candidate, the connection establishment failure process is called (step 142).

[0012]

In the conventional method as described above, the connection establishment failure notification DR_TPD is issued.
As a pattern in which U is transmitted from the relay system A93, for example, (1) when the route information to the partner system 92 is insufficient due to a definition error in the relay system A93,
(2) There is a case where data does not reach the partner system 92 due to a hardware error in the communication control device under the relay system A93 or a line error.

In these cases, the relay system A93 notifies the reception route of the connection establishment failure notification DR_TPD.
This is a case of sending U, that is, a case of detecting an abnormality before the data (connection establishment request) sent by the local system 91 reaches the partner system 92, and the sender of the connection establishment failure notification is the partner system 92. Instead, it is the relay system A93.

However, in the conventional processing, in such a case, the self-side system 91, which has received the connection establishment failure notification, does not discriminate the transmission source of the connection establishment failure notification and makes a "communication path establishment failure event". Is generated, it is determined that retry is unnecessary in step 132 shown in FIG. 9, and the connection establishment process is terminated without retrying the connection establishment process on the second and subsequent candidates. there were.

That is, in the conventional technique, in the received disconnection reason check process (step 132 in FIG. 9), the local system 91 determines whether to retry the connection establishment process by the OSI protocol, but fails in the connection establishment. Since the reason for the failure in establishing the connection is determined assuming that the notification is sent from the partner system 92, there is a problem that the opportunity for retry is limited.

The present invention solves the above problems and improves the reliability of the connection establishment process by increasing the chances of retrying by another route when the failure notification is received from the relay system in the connection establishment process. With the goal.

[0017]

In order to solve the above problems, the present invention has the following means as shown in FIG. 1, for example. In FIG. 1, 1 is a local system, 2 is a partner system, 3 is a relay system A, 4 is a relay system B, 5A ...
5E is a LAN device, 6A and 6B are WAN devices, 11 is a detailed code addition processing unit, 12 is a detailed code determination processing unit, 1
Reference numeral 3 represents a retry processing unit.

The detailed code addition processing unit 11 adds a detailed code for determining whether the failure is caused by the relay system A3 or the partner system 2 when the connection establishment fails in relaying the connection establishment request. It is means for returning a connection establishment failure notification to the requesting system (self system 1).

The detailed code determination processing unit 12 is means for determining the detailed code when the connection establishment failure notification is received from the relay system A3. If the connection establishment failure is caused by the relay system A3 according to the determination of the detailed code determination processing unit 11, the retry processing unit 13 uses another route that does not pass through the relay system A3 (route that passes through the relay system B4). It is a means to retry connection establishment.

[0020]

In the communication network form via the relay system, communication may not be possible depending on the state of the relay system rather than the state of the end systems. In the conventional technology, as described above, when the connection establishment failure notification for the transmitted connection establishment request is received, the connection establishment processing is terminated depending on the connection establishment failure reason, regardless of the transmission system. At this time, it may be possible to establish it by trying another route, but it has failed without retrying.

In the present invention, when the transmission source of the connection establishment failure notification in response to the transmitted connection establishment request is the relay system and the reason for the failure is, for example, "data non-arrival to the other system due to insufficient relay system environment". Then, retry the connection establishment process. As a result, it is possible to increase the pattern of retrying the connection establishment process and improve the reliability of the connection establishment process.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing an outline of the retry processing of the connection establishment processing in the embodiment. The network configuration shown in FIG. 2 is CLNP (Connectionless Network Protocol) in the N (Network) layer protocol in the OSI protocol.
ol) and CONP (Connection Network Protocol) are used as an example. The local system 1 is
It has two pieces of route information passing through the relay system A3 or the relay system B4 as route information for the partner system 2, and defines the LAN device 5A as the first candidate route and the LAN device 5B as the second candidate route.

When communicating with the partner system 2,
The connection establishment process is performed as follows. The local system 1 has the LA as the first candidate by definition.
The route using the N device 5A is selected, and the connection establishment request CR_TPDU (Connection Request Transport Pr
otocol Data Unit).

The relay system A3 is the local system 1
In order to relay the connection establishment request transmitted by the remote system 2 to the partner system 2, the relay is performed using the defined route. Here, the route information to the partner system 2 is insufficient due to a definition error in the relay system A3, or the relay system A3
When an error occurs such that the response data from the partner system 2 is not returned because the data does not reach the partner system 2 due to a hardware error in the subordinate communication control device or the like, a line error, etc., the relay system A3 It is determined that "connection establishment between the partner systems has failed".

When the relay system A3 recreates the connection establishment failure notification DR_TPDU from the received connection establishment request CR_TPDU, it newly adds a “detailed code of the reason for the local connection establishment failure” as a parameter value of the additional information parameter. The code to be added varies depending on the situation when the connection establishment failure is determined.

That is, in the detailed code, the transmission source type of the connection establishment failure notification DR_TPDU (information such as whether it is due to the relay system A3 or the partner system 2) and the reason for the connection establishment failure are the environment deficiencies of the relay system. The type of case and the like are added.

The local system 1 receives the connection establishment failure notification DR_TPDU with respect to the connection establishment request CR_TPDU transmitted to the partner system 2, and when a detailed disconnection reason detailed code is added to this, Sort the processing according to the detailed code.
If the reason for disconnection is, for example, "data did not reach the partner system 2 due to insufficient environment of the relay system A3", the connection establishment process is retried by another route.

In the connection establishment processing distributed as described above, the next candidate path (using the relay system B4) is selected, and the connection establishment request CR_
The TPDU is transmitted to the LAN device 5B.

When the relay system B4 receives the connection establishment request CR_TPDU transmitted by this process, the relay system B4 relays the connection establishment request CR_TPDU.
If there is no deficiency in the environment between 4 and the partner system 2, the data will reach the partner system 2 and the response will be returned from the partner system 2. As a result, the connection is established successfully.

In FIG. 3, the connection establishment failure notification DR_
A format example of "detailed code of failure reason for local connection establishment" added to TPDU is shown. Figure 3
In (A), 7 is DR_TPDU, 71 is TPDU length, 7
2 is a TPDU code, 73 is a partner transport connection reference number, 74 is a local transport connection reference number, 75 is a disconnection reason, 76 is a variable part, 77 is user data, 8 is an additional information parameter, 81 is a parameter code, 82 is a parameter length,
Reference numeral 83 represents a parameter value (variable length).

TPDU length 71, TPDU code 72, partner transport connection reference number 7
3, the local side transport connection reference number 74, the disconnection reason 75, and the additional information parameter 8 in the variable part 76 are parts defined by OSI. The additional information parameter 8 is composed of a parameter code 81, a parameter length 82, and a parameter value 83.
Store “Detailed code of the reason for failure of local connection establishment” in. The value of the parameter code 81 for this detailed code is "X'E0 '". Parameter value 83
Is a variable length m and is indicated by the parameter length 82.

FIG. 3B shows an example of the structure of the parameter value 83 in this embodiment. 84 is the format identifier, 85 is the location of the creator, 86 is the disconnect reason code, and 87 is the creator's NS.
AP address length, 88 indicates the NSAP address of the generator.

The format identifier 84 is information for identifying the reading format of this additional information and its target person. The creator's position 85 is information that distinguishes where in the network up to the partner system the system that generated this additional information parameter 8 is, and the following classifications are prepared.

00 to 7F (hexadecimal): Generated by the end system (partner system). 80 to FF (hexadecimal): generated by a non-terminating system (relay system). The disconnection reason code 86 is information representing a connection establishment failure reason code in a 4-byte area. Four
Of the byte codes, the first byte at the beginning is a major classification, the second byte is a reason classification, and the third and fourth bytes are more detailed classification codes.

The upper 4 bits of the major classification in the disconnection reason code 86 particularly represent the occurrence location of the cause event, and this is '0001' which is a definition in the host or a trouble in the equipment on the host side.
'0011' indicates that the protocol operation of the partner system is rejected, disconnected or abnormal, '0100' is rejected in the partner system or in the middle of the communication path, disconnected or no response event, '0110' is lack of resources or failure in the host, '0111' represents the cause of the transport service user. In addition, the lower 4 bits of the major classification represent the function or layer in which disconnection was detected, '0000' indicates various functions that refer to defined information,
'0001' is the physical layer, '0010' is the data link layer, '001
1'is the network layer and '0100' is the transport layer.

The creator's NSAP address length 87 is information indicating the length of the creator's NSAP address. The NSAP address 88 of the creator is information for identifying the system that created this additional information parameter 8.

Next, the processing in the local system 1 will be described. FIG. 4 shows the T (Transport) layer in the local system 1 that receives a connection establishment request from an upper layer, sends a connection establishment request (CR_TPDU), and receives a corresponding connection establishment failure notification (DR_TPDU). It is a figure which shows the outline of a process.

In FIG. 4, when the connection establishment request receiving unit 21 receives the connection establishment request from the upper layer, it requests the route selecting unit 24 to select a relay route, and the CR_TPDU creating unit 22 creates a CR_TPDU according to the result. The CR_TPD transmission unit 23 causes the CR_TPD
Send U to WAN / LAN circuit.

Next, when the connection disconnection request receiving unit 25 receives the DR_TPDU from the WAN / LAN circuit, it determines whether or not to retry the connection establishment by the processing shown in FIG. 5 described later. When retrying, a request is made to the route selecting unit 24 for relay route selection, and the connection establishment retrying unit 28 retries according to the result. That is, the CR_TPDU is created and transmitted again. When there is no unrouted relay route or when retry is not performed due to the disconnection reason, the connection disconnection instruction creating unit 26 creates a connection disconnection instruction, and the connection disconnection instruction sending unit 27 sends the connection disconnection instruction to the upper layer. To do.

FIG. 5 shows a processing flow when the local system 1 receives the connection establishment failure notification. In step S1, connection establishment failure notification DR_TP
Accept the DU and start processing.

In step S2, DR_TP shown in FIG.
The existing disconnection reason 75 of the DU 7 is judged, and if a retry is necessary, the process proceeds to step S3, and if the retry is unnecessary, the process proceeds to step S12.

In step S3, the tried route is WAN.
Check whether it is a route or a LAN route.
In step S4, the presence / absence of a use route candidate having the same attribute (WAN / LAN) is determined. If there is a candidate, the process in step S5 is performed. If there is no candidate, the use route attribute is changed and the process in step S8 is performed. To do.

In step S5, the connection establishing process is started. The connection establishment request CR_TPDU is created in step S6, and the connection establishment request CR_TPDU is sent in step S7.

In step S8, the attribute of the route is changed and the connection establishing process is started. In step S9, it is determined whether or not there is a candidate for the use route, and if there is no candidate, the process proceeds to step S19. If there is a candidate, step S1
0 creates a connection establishment request CR_TPDU, and step S11 creates a connection establishment request CR
Send _TPDU.

If the existing disconnection reason 75 is judged and it is judged that the retry is unnecessary, the format identifier 84 stored in the parameter value 83 shown in FIG. 3 is checked in step S12, and if it is possible to refer, the step is carried out. The process proceeds to S13, and if the reference is impossible, the process proceeds to step S19.

In step S13, the position 85 of the generator stored in the parameter value 83 is checked. If the position 85 of the generator is a non-terminating system (relay system), the process proceeds to step S14 and the position 85 of the generator is terminated. If it is a system (partner system), the process proceeds to step S19.

In step S14, the disconnection reason code 86
Is checked, and if retry is required, the process proceeds to step S15, and if retry is not required, the process proceeds to step S19. In step S15, it is determined whether or not there is a route different from the system of the creator NSAP address 88. If there is a different route, the process proceeds to step S16, and if there is no different route, the process proceeds to step S19.

In step S16, the connection establishing process is started, the connection establishing request CR_TPDU is created in step S17, and the connection establishing request CR_TPDU is sent in step S18.

In step S19, connection establishment failure processing is called. FIG. 6 is a diagram showing a processing outline of the relay system in the embodiment of the present invention. Relay system A
In 3, the WAN / LAN circuit to the relay data reception unit 31
When the CR_TPDU is received, the request is sent to the route selection unit 34 to check the presence / absence of the relay route having the same attribute. If there is a relay route, the relay data transmission unit 32 transmits the relay data. If there is no relay route, the connection establishment request reception unit 33 is called. The connection establishment request acceptance unit 33 requests the route selection unit 34 to determine whether or not there is a trial route. If there is a trial route, CR_TPDU creation unit 3
Create a new CR_TPDU with step 5, CR_TPD
WAN / connecting to the partner system 2 by the U sending unit 36
Send CR_TPDU to the LAN circuit. with this,
The retransmission timer control unit 37 monitors the response time.

If there is no trial route due to a definition error of the relay system A3, the connection establishment request acceptance unit 33
The connection disconnection request creation unit 38 is called. The connection disconnection request creation unit 38 creates a connection establishment failure notification (= connection disconnection request) DR_TPDU. Then, the connection disconnection request transmission unit 39 causes D
Send R_TPDU to WAN / LAN circuit.

If no response is returned within the predetermined time, the connection disconnection request acceptance unit 40 causes the DR_TPD
When U is received, the protocol error detection notification reception unit 41 determines that the protocol error detection notification ER_TPDU
If the connection is accepted, the connection disconnection request creation unit 3
8 creates a DR_TPDU, and the connection cut request sending unit 39 sends the DR_TPDU to the WAN / LAN circuit.

Here, in the prior art, when the connection disconnection request preparation unit 38 prepares a connection disconnection request (connection establishment failure notification), even in the case of a communication connection disconnection not addressed to itself, it is prepared by the same method as that of the partner system. However, in the present embodiment, in the case of disconnecting a communication connection not addressed to itself (relay system A3), a new detailed code of the local disconnection reason is newly added to the additional information parameter 8 to be created. .

In the embodiment of the present invention described above, an example in which CLNP of the OSI protocol is used has been shown to facilitate the description. This is realized by the T (Transport) layer of OSI, but when the local system, the relay system, and the partner system use the OSI protocol, the same applies to the following connection establishment processing. Is possible.

(1) Connection establishment processing executed through the OSI7 layer. (2) Connection establishment processing regardless of the network type (LAN / WAN, etc.) used between the partner systems.

(3) Connection establishment processing between relay systems that does not close between the local system and the relay system.

[0056]

As described above, according to the present invention,
Since the detailed code of the local disconnection reason is added to the connection establishment failure notification for the connection establishment request,
By determining this, it is possible to increase the number of cases that can be retried and improve the reliability in the connection establishment process.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of the present invention.

FIG. 2 is a diagram illustrating an outline of connection establishment processing according to the embodiment of this invention.

FIG. 3 is a diagram showing a format of a detailed code according to the embodiment of the present invention.

FIG. 4 is a diagram showing an outline of connection establishment processing of a local system according to an embodiment of the present invention.

FIG. 5 is a flowchart of a connection establishment process of the local system according to the embodiment of this invention.

FIG. 6 is a diagram showing a processing outline of the relay system in the embodiment of the present invention.

FIG. 7 is a diagram for explaining a conventional technique.

FIG. 8 is a flow chart of a route selection process in a relay system of the related art.

FIG. 9 is a retry processing flowchart in the conventional system of the own side.

[Explanation of symbols]

 1 own system 2 partner system 3 relay system A 4 relay system B 5A to 5E LAN device 6A to 6B WAN device 11 detailed code addition processing unit 12 detailed code determination processing unit 13 retry processing unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04L 12/46 12/28 29/08 9371-5K H04L 13/00 307 A

Claims (2)

[Claims] 1. A request source system which sends a connection establishment request to a partner system (2) via a relay system (3/4).
In the communication system for establishing communication between (1) and the partner system (2), the relay system
(3/4) adds a detailed code that can be used to determine whether the failure was due to the relay system (3/4) or the partner system (2) when connection establishment failed in relaying the connection establishment request. Means (11) for returning a connection establishment failure notification to the requesting system (1),
When the system (1) that has issued the connection establishment request receives the connection establishment failure notification from the relay system (3/4), it judges the detailed code and the establishment of the connection is relayed to the relay system (3/4). A communication system characterized by comprising processing means (12, 13) for retrying the connection establishment processing through another route that does not go through the relay system (3/4) if the failure is caused. 2. A request source system that sends a connection establishment request to a partner system (2) via a relay system (3/4).
In a connection establishment processing method in a communication system in which a connection is established between (1) and the partner system (2), the system (1) that issues a connection establishment request is connected to the partner system (2). Relay system (3 /
4) has the information defining a plurality of communication routes, and makes a connection establishment request using one of the communication routes, and stores the trial route of the connection establishment process, the unestablished route of the connection establishment process, or both of them. However, the relay system (3 /
When the connection establishment fails, 4) adds a detailed code that can determine whether the failure is caused by the relay system (3/4) or the partner system (2) and requests the connection establishment failure notification. Reply to the system (1) of
The system (1) that received the connection establishment failure notification
The detailed code in the connection establishment failure notification is determined, and when the establishment of the connection is a failure due to the relay system (3/4), the connection establishment processing is performed on an untried route that does not pass through the relay system (3/4). A connection establishment processing method characterized by retrying.